[PATCH v2] Documentation: checkpatch: add UNNECESSARY_CASTS message.

[PATCH v2] Documentation: checkpatch: add UNNECESSARY_CASTS message.

[Vinesh Raut]

Add verbose description for UNNECESSARY_CASTS message type.

Suggested-by: Lukas Bulwahn <lukas.bulwahn@gmail.com>
Signed-off-by: Vinesh Raut <vineshraut2017@gmail.com>
---
 Documentation/dev-tools/checkpatch.rst | 9 +++++++++
 1 file changed, 9 insertions(+)

diff --git a/Documentation/dev-tools/checkpatch.rst b/Documentation/dev-tools/checkpatch.rst
index f0956e9ea2d8..9cb6b9059fc6 100644
--- a/Documentation/dev-tools/checkpatch.rst
+++ b/Documentation/dev-tools/checkpatch.rst
@@ -268,6 +268,15 @@ Allocation style
 
     See: https://www.kernel.org/doc/html/latest/core-api/memory-allocation.html
 
+   **UNNECESSAR_CASTS**
+   Cast should not be done to any alloc functions.
+   Appropriate type of pointer is pick by compiler at run time
+   Cast may hide bugs, as compiler suppress the warning after cast.
+
+   See:
+   1] https://lore.kernel.org/lkml/20070808024321.GA6316@redhat.com/
+   2] https://lore.kernel.org/lkml/a5e60a2b93e10baf84af063f6c8e56402273105d.camel@perches.com/
+
 
 API usage
 ---------
-- 
2.30.2

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Re: [PATCH v2] Documentation: checkpatch: add UNNECESSARY_CASTS message.

[Vinesh Vilas Raut]

On Fri, Aug 6, 2021 at 8:49 PM Vinesh Raut <vineshraut2017@gmail.com> wrote:

>
>      See: https://www.kernel.org/doc/html/latest/core-api/memory-allocation.html
>
> +   **UNNECESSAR_CASTS**
spelling mistake
**UNNECESSARY_CASTS**
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Re: [PATCH v2] Documentation: checkpatch: add UNNECESSARY_CASTS message.

[Dwaipayan Ray]

On Fri, Aug 6, 2021 at 8:49 PM Vinesh Raut <vineshraut2017@gmail.com> wrote:
>
> Add verbose description for UNNECESSARY_CASTS message type.
>
> Suggested-by: Lukas Bulwahn <lukas.bulwahn@gmail.com>
> Signed-off-by: Vinesh Raut <vineshraut2017@gmail.com>
> ---
>  Documentation/dev-tools/checkpatch.rst | 9 +++++++++
>  1 file changed, 9 insertions(+)
>
> diff --git a/Documentation/dev-tools/checkpatch.rst b/Documentation/dev-tools/checkpatch.rst
> index f0956e9ea2d8..9cb6b9059fc6 100644
> --- a/Documentation/dev-tools/checkpatch.rst
> +++ b/Documentation/dev-tools/checkpatch.rst
> @@ -268,6 +268,15 @@ Allocation style
>
>      See: https://www.kernel.org/doc/html/latest/core-api/memory-allocation.html
>
> +   **UNNECESSAR_CASTS**
> +   Cast should not be done to any alloc functions.
> +   Appropriate type of pointer is pick by compiler at run time
s/run time/runtime

> +   Cast may hide bugs, as compiler suppress the warning after cast.

The question which arises here is what kind of bug is suppressed.
Maybe follow http://c-faq.com/malloc/mallocnocast.html as checkpatch
says to write up a paragraph on why it is bad.

> +
> +   See:
> +   1] https://lore.kernel.org/lkml/20070808024321.GA6316@redhat.com/
> +   2] https://lore.kernel.org/lkml/a5e60a2b93e10baf84af063f6c8e56402273105d.camel@perches.com/

These links are just patches that introduced the test. There is not much
information about "why" they were introduced.

Other than that change the enumeration type to be
uniform with the rest of the documentation maybe?
The thing followed till now is:

See:
  1. link_1
  2. link_2

Dwaipayan.
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Re: [PATCH v2] Documentation: checkpatch: add UNNECESSARY_CASTS message.

[Vinesh Vilas Raut]

On Sat, Aug 7, 2021 at 1:36 AM Dwaipayan Ray <dwaipayanray1@gmail.com> wrote:
>
> On Fri, Aug 6, 2021 at 8:49 PM Vinesh Raut <vineshraut2017@gmail.com> wrote:
> >
> > Add verbose description for UNNECESSARY_CASTS message type.
> >
> > Suggested-by: Lukas Bulwahn <lukas.bulwahn@gmail.com>
> > Signed-off-by: Vinesh Raut <vineshraut2017@gmail.com>
> > ---
> >  Documentation/dev-tools/checkpatch.rst | 9 +++++++++
> >  1 file changed, 9 insertions(+)
> >
> > diff --git a/Documentation/dev-tools/checkpatch.rst b/Documentation/dev-tools/checkpatch.rst
> > index f0956e9ea2d8..9cb6b9059fc6 100644
> > --- a/Documentation/dev-tools/checkpatch.rst
> > +++ b/Documentation/dev-tools/checkpatch.rst
> > @@ -268,6 +268,15 @@ Allocation style
> >
> >      See: https://www.kernel.org/doc/html/latest/core-api/memory-allocation.html
> >
> > +   **UNNECESSAR_CASTS**

+   **UNNECESSARY_CASTS**

> > +   Cast should not be done to any alloc functions.
> > +   Appropriate type of pointer is pick by compiler at run time

+   Appropriate type of pointer is pick by compiler at runtime

> s/run time/runtime
>
> > +   Cast may hide bugs, as compiler suppresses the warning after cast.


+   If a pointer is cast (wrongly), bugs like memory corruption,
segmentation faults can occur.
+   Also, It can affect functionality of the program.


>
> The question which arises here is what kind of bug is suppressed.
> Maybe follow http://c-faq.com/malloc/mallocnocast.html as checkpatch
> says to write up a paragraph on why it is bad.
>
> > +
> > +   See:
> > +   1] https://lore.kernel.org/lkml/20070808024321.GA6316@redhat.com/
> > +   2] https://lore.kernel.org/lkml/a5e60a2b93e10baf84af063f6c8e56402273105d.camel@perches.com/
>
> These links are just patches that introduced the test. There is not much
> information about "why" they were introduced.

Should I remove it?
And I didnt found any discussion on LKML regarding  UNNECESSARY_CASTS issue,
other than this patches.

>
> Other than that change the enumeration type to be
> uniform with the rest of the documentation maybe?
> The thing followed till now is:
>
> See:
>   1. link_1
>   2. link_2

+   See:
+   1. https://lore.kernel.org/lkml/20070808024321.GA6316@redhat.com/
+   2. https://lore.kernel.org/lkml/a5e60a2b93e10baf84af063f6c8e56402273105d.camel@perches.com/

>
> Dwaipayan.
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